Apparatus and method for forming cohesive filamentary tows



March 4, 1969 0. GABBlTUS ETAL 3,430,427

APPARATUS AND METHOD FOR FORMING COHESIVE FILAMENTARY TOWS Filed Feb. 6. 1967 United States Patent 3,430,427 APPARATUS AND METHOD FOR FORMING COHESIVE FILAMENTARY TOWS Derek Gabbitus, Allan Stephens, James Brebuer, and Anthony Michael Lee, Doncaster, England, assignors to Imperial Chemical Industries, Limited, London, England a corporation of Great Britain Filed Feb. 6, 1967, Ser. No. 614,198 Claims priority, application Great Britain, Feb. 17, 1966,

7,026/ 66 US. Cl. 57-34 10 Claims Int. Cl. Dtllh 5/22, 13/30; D01d 11/00 ABSTRACT OF THE DISCLOSURE This invention relates to improvements in the formation of continuous filamentary tows from melt-spun linear high molecular weight polymers, and is especially concerned with the formation of tows from heavy denier filaments, that is filaments of denier or more.

In the production of staple fibres from continuous filamentary material as aforementioned, such as nylon, the filaments may first be wound up onto containers to form yarn packages in the normal way after extrusion and subsequently formed into a tow by withdrawing the yarns from a plurality of such packages placed on a creel and then compacting the filaments, for example, by inserting a limited degree of crimp, to form a unitary tow, which tow is then further processed by drawing, crimping and cutting to staple length fibres. A preferred method of forming a tow is described in British patent specification No. 742,397. In this method filaments of a melt-spun synthetic linear polymer, such as nylon, are, after solidification, brought together and introduced into a compacting device comprising two co-acting pressure rollers which form them into a lightly cohering tow such that the filaments are capable on subsequent processing of resuming their separate identities.

After formation the tow is normally stored in cans from which it can be subsequently withdrawn for processing into staple fibres. Conveniently the tow is laid in the cans by the action of air distributors and deflector plates as, for example, described in British patent specification No. 742,398.

The aforementioned preferred process for forming a tow yields a highly compact structure in which there is good cohesion between the filaments when employed in the formation of tows from filaments of relatively low denier, that is 6 or 8 denier. However, with tows formed from filaments of heavy denier, eg 10 d.p.f. and especially tows formed from filament bundles having a total denier 100 kilo denier (kd.) or more, there is insufiicient cohesion between the filaments and the tows tend to be inadequately compacted, As a result the non-compacted filaments tend to entangle with each other in the cans in which the tow is stored making removal of the tow difiicult and leading to excessive processing difiiculties, for example, in drawing. In extreme cases the tow cannot be removed from the cans sufliciently readily to enable it to be processed further.

In the process described in British patent specification No. 742,393, the bundle of filaments which is to form the tow is introduced to the compacting device via a funnel guide. We have now found that if a current of compressed air is introduced into the funnel guide such that its major component of motion is in a direction opposite to that of the movement of the tow, good inter-filament cohesion is obtained and a highly compacted tow is produced by the said compacting device with both tows formed from heavy denier filaments and tows of greater than kd.

Accordingly therefore, from one aspect, the present invention provides a process for the formaiton of a compact filamentary tow from filaments of a melt spun linear high molecular weight polymer wherein a plurality of filaments are gathered together into a bundle, the filament bundle forwarded through a funnel guide, into which a current of compressed air is blown, and into a compacting device to provide a tow having good interfilament cohesion, the said current of compressed air having its major component of motion in a direction opposite to that of the movement of the filament bundle.

Preferably the filaments are gathered together soon after extrusion but after solidification.

A suitable compacting device comprises a pair of coacting pressure rollers between which the filament bundle passes and which form the filaments into a cohering compact tow, such that the said filaments are capable on subsequent processing of resuming their separate identities.

Whilst the above process is particularly suited to tows formed from filaments having a denier of 10 and above and for tows formed from filament bundles of greater than 100 kd., it may also be usefully applied to other tows.

From another aspect the present invention provides an apparatus for compacting melt spun filaments of a synthetic linear high molecular weight polymer into a tow comprising a funnel guide and compacting device, said funnel guide comprising a base plate, an expansion cover consisting of a lower portion fixed to the said base plate and an upper portion adapted to be slideably moveable within said lower fixed portion, a guide tube consisting of two separate portions and means for introducing air at an acute angle to the axis of the guide tube, the upper portion of the said expansion cover having one portion of guide tube passing therethrough and the lower portion of the cover having the other portion of the guide tube passing therethrough one end of the guide tube portion extending beyond the base plate on the side remote from the cover, the two guide-tube portions being axially aligned but out of contact with each other, and the means for introducing compressed air into the guide tube being positioned at a point in the end of the guide-tube portion extending beyond the base plate on the side remote from the cover.

A guide funnel suitable for use in the present process is shown in the accompanying drawing.

In the drawing a base plate 1 contains the lower portion of the guide funnel 2 protruding therethrough, an expansion cover 3 consisting of a fixed lower portion 4 and an upper portion 5 which is mounted to be move-able vertically within the fixed lower portion, the said moveable upper portion 5 containing in the top thereof the upper portion 6 of the funnel guide such that there is a gap 7 between the upper and lower portions of the funnel guide. An inlet pipe 8 for the compressed air is inserted into the funnel guide below the level of the base plate such that the compressed air will have its major component of motion upwards through the funnel guide. A collector tray 9 is positioned at the base of the expansion cover and has drain holes 10. In order that the present invention may be more clearly understood, one convenient process will now be described with reference to the aforementioned drawing.

A filament bundle of total denier 193 kd. formed by gathering together filaments from a melt spinning apparatus containing 20 spinnerets from each of which 210 filaments of undrawn denier 46 d.p.f. may be spun together. Prior to being formed into a bundle, the filaments from each spinneret are solidified by cooling with air in the normal way and combined into a bundle at a convergence guide. The bundle of filaments is then threaded through the funnel guide, with the moveable portion of the expansion cover in its lower-most position, into the compacting device. After the bundle has been introduced into the compacting device, the upper moveable portion of the expansion cover is raised to its uppermost position to widen the gap 7 between the upper and lower portions of the funnel guide. A current of air at a pressure of 45 lbs./ sq. in. gauge is introduced through the pipe 8 into the funnel guide and flows upwardly therethrough, the tow being drawn downwardly through the funnel guide by the nip rolls 1 of the compacting device, the current of air causes moisture to be blown off from the tow in the funnel guide, which moisture collects on the walls of the expansion cover and runs down into the collector tray 9 and out through the drain holes 10 into suitable collector device.

The precise action of the compressed air on the bundle of filaments is not fully understood, but it is thought that a certain degree of false twist may be inserted into the bundle of filaments and at the same time causes some interlacing of the filaments. Whatever the nature of the current of air on the bundle of filaments, the efiect is to obtain a more cohesive tow from the nip rolls of the compacting device.

What we claim is:

1. A process for the formation of a compact filamentary tow from filaments of a melt spun linear high molecular weight polymer wherein a plurality of filaments in a substantially parallel relationship are gathered together into a bundle, the filament bundle forwarded through a funnel guide, into which a current of compressed air is blown, and into a compacting device to provide a tow having good interfilament cohesion, the said current of compressed air having its major component of motion in a direction opposite to that of the movement of the filament bundle and acting on said bundle in a manner to increase interfilament cohesion in the compacted tow.

2. A process according to claim 1 wherein the filaments are gathered together soon after extrusion but after solidification.

3. A process according to claim 2 wherein the compacting device comprises two coacting pressure rollers between which the filament bundle passes.

4. A process according to claim 1 wherein the filament denier is at least 10.

5. A process according to claim 1 wherein the filament bundle has a total denier of at least 100 kilo denier.

6. Apparatus for compacting melt spun filaments of a synthetic linear high molecular weight polymer into a tow comprising a funnel guide and compacting device, said funnel guide comprising a base plate, an expansion cover consisting of a lower portion fixed to the said base plate and an upper portion adapted to be slideably moveable within said lower fixed portion, a guide tube consisting of two separate portions and means for introducing air at an acute angle to the axis of the guide tube, the upper portion of the said expansion cover having one portion of guide tube passing therethrough and the lower portions of the cover having the other portions of the guide tube passing therethrough one end of the guide tube portion extending beyond the base plate on the side remote from the cover, the two guide-tube portions being axially aligned but out of contact with each other, and the means for introducing compressed air into the guide tube being positioned at a point in the end of the guide-tube portion extending beyond the base plate on the side remote from the cover.

7. Apparatus according to claim 6 wherein the compacting device comprises a pair of coacting pressure rollers.

8. In a method of forming a filamentary tow which comprises bringing together in substantially parallel rela tionship a plurality of melt-spun linear high molecular weight polymer filaments into a bundle and forwarding the bundle through a funnel guide to a nip-type compacting device which forms the filaments into a tow, the improvement which increases the interfilamenta-ry cohesion produced by the compacting device, said improvement comprising subjecting the bundle of filaments in the funnel guide to the action of a stream of air by blowing a current of compressed air into the funnel guide such that its major component of motion is in a direction opposite to the movement of the tow.

9. A process as in claim 8 wherein the filament denier is at least 10.

10. A process as in claim 8 wherein the filament bundle has a denier of at least kilo denier.

References Cited UNITED STATES PATENTS 3,115,691 12/1963 Bunting et al 28-1 3,302,386 2/1967 Gonsalves 57-34 XR 3,333,313 8/1967 Gilmore et a1 28-1 2,302,790 11/ 1942 Modigliani 28-1 2,869,967 1/ 1959 Breen 5734 XR 2,942,402 6/1960 Palm 5734 2,958,112 11/1960 Hall 57-34 X=R 3,009,309 11/1961 Breen et al 57-139 3,188,713 6/1965 Dyer et al 57-34 XR 3,253,313 5/1966 Head 28-1 3,340,684 9/ 1967 Shichman.

DONALD WATKINS, Primary Examiner.

US. Cl. X.R. 

